The invention relates to a device for determining the spatial position of a teat of an animal.
Such a device is known from the International Patent Application No. 98/00460, of Fransen et al, published Feb. 25, 1999, WO 99/09430, and its equivalent U.S. Pat. No. 6,118,118, of Van der Lely et al, which issued Sep. 12, 2000. although this device functions satisfactorily and is adapted to determine highly accurately the position of a teat, in some cases, such as for tilting teats, it appears to be desirable to improve the determination of the position.
It is an object of the invention to provide a device for determining the spatial position of a teat of an animal, said device enabling an improved determination of the position.
For that purpose, according to a first aspect of the invention, a device for determining the spatial position of a teat animal which comprises a transmitted element for transmitting a first ray or beam of rays in a first sub-area of space and a further transmitter element for emitting a second ray or beam of rays to a second sub-area of space, a first receiver to receive a reflection of the first ray or beam of rays, a second receiver element arranged to receive a reflection of the second ray or beam of rays, a mirror that rotates about an axis of rotation for directing the ray or beam of rays from each transmittal element in a relevant plane of the relevant sub-area of space for directing a ray or beam of rays from the relevant receiver element, or doing both, and means for directing the ray or beam or rays from each transmittal element in at least two spaced-apart relevant position determination surfaces of the relevant sub-area of space.
Because at least two spaced-apart position determination surfaces, a more accurate determination of the position is possible due to the fact that there is also obtained a determination of the position in height of the teat, so that tilt of the teat can be determined.
In an embodiment of a device according to the invention, the mirror is constituted by a polygon having at least two reflective surfaces, at least one of the reflective surfaces being at a different angle relative to the axis of rotation than one of the remaining reflective surfaces. Due to the fact that a polygon is used, there is obtained in a simple constructive manner a synchronisation of the rotation of the reflective surfaces. As a result thereof the further processing of the data is also simplified.
The device is preferably provided with a means for directing the ray or beam of rays emanating from each transmitter element in three spaced-apart relevant position determination surfaces of the relevant sub-area of the space. In practice it has appeared that the use of three position determination surfaces in almost all cases suffices for determining the position of a teat.
In an embodiment of a device according to the invention the mirror is constituted by a pentagon having five reflective surfaces, one of the reflective surfaces being parallel to the axis of rotation, two of the reflective surfaces being at an equal positive angle relative to the axis of rotation, and the remaining two reflective surfaces being at an equal negative angle relative to the axis of rotation. Thus there are obtained three position determination surfaces, the two outer surfaces being scanned twice at one rotation of the pentagon. Thus there can be obtained a very accurate determination of the position, in particular tilt determination, of a teat. It is especially advantageous when the positive and negative angle are between approximately 3 degrees and approximately 13 degrees.
In an alternative embodiment of a device according to the invention, two of the reflective surfaces are parallel to the axis of rotation, one of the reflective surfaces being at a first angle relative to the axis of rotation, and the remaining two reflective surfaces being at a second angle relative to the axis of rotation. The first angle is preferably between approximately 1 degree and approximately 7 degrees, whereas the second angle is preferably between approximately 1 degree and approximately 20 degrees. An especially accurate determination of the position of a teat is obtained when the second angle is at least approximately twice as great as the first angle.
The invention further relates to a device for determining the position of a teat of an animal relative to the device, said device being provided with a transmitter element for emitting a ray or beam of rays, with at least one receiver element arranged to receive a ray or beam of rays reflected by a teat, and with at least one reflective surface which is rotatable about an axis of rotation for directing the ray or beam of rays emanating from the transmitter element consecutively to a teat or for directing the ray or beam of rays emanating from a teat to the receiver element, or doing both, characterized in that there are provided means for changing the orientation of the reflective surface relative to the teat during rotation of the reflective surface. Due to the fact that there are provided means for changing the orientation of the reflective surface relative to the teat during rotation of the reflective surface, during rotation there are obtained several surfaces in which the ray respectively beam of rays is emitted. Due to this, besides determination of the position, also determination of the position in height of a teat is possible, so that tilt of the teat can be determined. The synchronisation of the change and the data obtained therefrom may be realised by means of a computer, so that processing of the data can take place accurately. It will be obvious that, on the one hand, the change in orientation may be gradual, that is continuous, but that, on the other hand, a discrete change of orientation may take place as well.
The means are preferably suitable for changing the orientation of the reflective surface relative to the axis of rotation. Additionally or alternatively the means are suitable for changing the orientation of the axis of rotation. Such a change may take place e.g. by means of an eccentric suspension or a curve disc or the like.
The invention further relates to a device for determining the position a teat of an animal relative to the device, said device being provided with a transmitter element for emitting a ray or beam of rays, with at least one receiver element arranged to receive a ray or beam of rays reflected by a teat, and with a mirror which is rotatable about an axis of rotation for directing the ray or beam of rays emanating from the transmitter element consecutively to a teat or for directing the ray or beam of rays emanating from a teat to the receiver element, or doing both, characterized in that the mirror is constituted by a polygon having at least two reflective surfaces, at least one of the reflective surfaces being at a different angle relative to the axis of rotation than one of the remaining reflective surfaces. Due to the fact that there are at least two reflective surfaces, at least one of the reflective surfaces being at a different angle relative to the axis of rotation than one of the remaining reflective surfaces, there are obtained at least two spaced-apart surfaces in which the ray or respectively beam of rays is emitted. Due to this, besides determination of the position, also determination of the position in height of a teat is possible, so that tilt of a teat can be determined. It will be appreciated that the orientation of the reflective surfaces relative to the axis of rotation may be fixed as well as variable. Further also in this situation the orientation of the axis of rotation may be variable.
An optimal determination of the position of teats appears to be possible when the mirror is constituted by a pentagon having five reflective surfaces.
A particularly accurate determination of not only the position but also of tilt is obtained when one of the reflective surfaces is parallel to the axis of rotation, two of the reflective surfaces are at an equal positive angle relative to the axis of rotation, and the remaining two reflective surfaces are at an equal negative angle relative to the axis of rotation. As a result thereof there are obtained three detection surfaces, the outer surfaces being created by rays or beams of rays emanating from two reflective surfaces, and thus providing a double measurement. The positive and negative angle are preferably between approximately 3 degrees and approximately 13 degrees.
Alternatively there is obtained a particularly accurate determination of the position and the tilt when two of the reflective surfaces are parallel to the axis of rotation, one of the reflective surfaces is at a first angle relative to the axis of rotation, and the remaining two reflective surfaces are at a second angle relative to the axis of rotation.
The first angle is preferably between approximately 1 degree and approximately 7 degrees. The second angle is preferably between approximately 1 degrees and approximately 20 degrees. Accurate data when the second angle is at least approximately twice as great as the first angle.
For the purpose of accurately determining the position of two teats disposed behind each other relative to the device, the device further comprises means for scanning the space in at least two sub-areas substantially simultaneously. This is preferably obtained in that the device is provided with means for directing at least two separate rays or beams of rays to different areas in that space. When the transmitter elements are alternately switched on and off, a processor which processes the data obtained from the two transmitter elements will suffice. For the purpose of obtaining a simplified assembly of the device, the transmitter element, the receiver element and the directional element are mounted on a bottom plate so as to form a unit. The device is then assembled by accommodating the bottom plate including elements in a housing having a window for letting through the ray or beam of rays emanating from the transmitter element or from a teat, or from both, shock-absorbing means being provided between the housing and the bottom plate. As a result thereof shocks exerted on the housing are not transferred or are transferred to a lesser extent to the sensitive components of the device.
To prevent undesired reflection, the window is designed as a flat window and is at an angle relative to the normal on the bottom plate.
The device is preferably provided with a dirt detector for detecting contamination of the window. When contamination is detected, the dirt detector may supply a signal to the operator of the device or to an automatic device for cleaning the window. Such a dirt detector may be constituted by separate receiver elements detecting the rays or beams of rays reflected by the window. The device is preferably provided with anti-condensation means for preventing or removing or reducing condensation on the inner side of the window, so that the rays or beams of rays are not affected when passing through the window. The anti-condensation means preferably comprise a heating means which is integrated into the window. The heating means is particular active continuously, in other words, independently of the environmental conditions. As a result thereof the reflective surface, independently of quickly varying environmental conditions, is always free from condensation, which enhances the determination of the position.
Consequently, the invention also relates to a device for determining the position of a teat of an animal relative to the device, said device being provided with a transmitter element for emitting a ray or beam of rays, with at least one receiver element arranged to receive a ray or beam of rays reflected by a teat, and with at least one reflective surface which is rotatable about an axis of rotation for directing the ray or beam of rays emanating from the transmitter element consecutively to a teat or for directing the ray or beam of rays emanating from a teat to the receiver element, or for doing both, characterized in that the device comprises a housing having a window for letting through the ray or beam of rays emanating from the transmitter element or emanating from a teat, or both the device being provided with a heating means which is integrated into the window, the heating means being active continuously, in other words independently of the environmental conditions.
A further protection against moisture in the housing is obtained when, except the window, the inner side of the walls of the housing is provided with an aluminium coating.
The device according to the invention is especially suitable for use in a milking device for milking animals, such as cows, provided with at least one milking compartment comprising at least one milking robot having a robot arm for automatically connecting teat cups to the teats of an animal to be milked, the device being used for determining the position of a teat relative to a teat cup.
A milking device in which the device for determining the position of the teat is disposed in a shock-resistant manner is obtained when the housing is covered with a lid that is supported by the robot arm. The lid is preferably composed of stainless steel.